Productivity, pathogenicity, host range, and spore mass-propagation of local strain of Mattesiasp. isolated from insect cadavers of certain stored grain pests in Egypt

Average yields of Mattesiaspores (spore productivity) had varied from a minimum yield (0.17 ×107spores) for Laemophloeus turcicusadult to a maximum yield (7.46 ×107spores) for Plodia interpunctellalarva. Comparatively, the highest increase in Mattesiaspore yield, recorded from P. interpunctellalarva (7.46 × 107spores) over the lowest one, estimated for L. turcicusadult (0.17 ×107spores), was nearly 44-fold. The increase in Mattesiaspore yields that calculated from the other hosts (P. interpunctellapupa or moth; Galleria mellonellalarva; Rhyzopertha dominicaadult; Sitophilus zeamais), over that estimated for L. turcicusadult, was less than 10-fold (6–9-fold). Based on the weight of 1 g of the insect host infected with Mattesiasp., small stored grain insect hosts (e.g. L. turcicus, S. zeamais, and R. dominica) seemed to achieve Mattesiaspore yields more than the larger ones (e.g. P. interpunctella). The increase in spore yields over that used for the inoculum, based on an average of 25 P. interpunctellalarvae per bioassay container, was ca. 2 to 31-fold. These results revealed that the Indianmeal moth, P. interpunctella, could serve as a potential host for mass propagating the isolated entomopathogenic protozoan, Mattesiasp. Besides Mattesialarval mortality, survivors of Mattesiainfection suffered deformities and noticeable undersized pupae or adults than the control ones. Also, many copulated moths (ca.46%) were unable to become separated after copulation until they had died. Bioassay of siftings, obtained from L. turcicus-protozoan-infected stock cultures, was carried out in order to emphasize the suppressive potent role of such protozoan entomopathogens in long-term storage. With the highest tested concentration of the studied siftings (10%), mortality responses due to Mattesiainfection ranged from 13 to 68% at 14–169 days post-treatment. The corresponding figures for Adelinainfection were 7–42%.